The present invention relates to quantum computing, and more specifically, to suspended superconducting qubits and methods of manufacturing the same.
Superconducting quantum circuits containing Josephson junctions are currently being pursued as the information-storing building blocks (i.e., quantum bits, or qubits) of a quantum computer. A basic challenge towards this goal is developing devices whose quantum coherence lasts long enough to enable control and measurement with error rates below the bounds requisite for quantum error correction. Lossy materials within the mode volume of superconducting resonant structures impose a limit on how long such systems can store energy. Reducing the participation ratio of energy-storing non-vacuum materials (inclusive of surfaces, interfaces, thin films, and bulk matter) within the mode volume increases this limit. In particular, two-level systems present at surfaces and interfaces of superconducting qubits are believed to be a significant source of decoherence. The substrate-to-metal interface and substrate-to-air interface are believed to be a source of loss. Typical superconducting qubits are manufactured with aluminum thin films deposited on an insulating substrate of silicon or sapphire.